tor-browser

Blur.h (6218B)

---

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef MOZILLA_GFX_BLUR_H_
#define MOZILLA_GFX_BLUR_H_

#include "mozilla/gfx/Rect.h"
#include "mozilla/gfx/Point.h"
#include "mozilla/gfx/Types.h"

class SkSurface;

namespace mozilla {
namespace gfx {

class DrawTargetSkia;

#ifdef _MSC_VER
#  pragma warning(disable : 4251)
#endif

/**
* Implementation of a Gaussian blur.
*
* A Gaussian blur is good for blurring because, when done independently
* in the horizontal and vertical directions, it matches the result that
* would be obtained using a different (rotated) set of axes.
*
* This is a "service" class; the constructors set up all the information
* based on the values.
* The callers are responsible for creating and managing the backing surface
* and passing the pointer to the data to the Blur() method.  This class does
* not retain the pointer to the data outside of the Blur() call.
*
* A spread N makes each output pixel the maximum value of all source
* pixels within a square of side length 2N+1 centered on the output pixel.
*/
class GFX2D_API GaussianBlur final {
public:
 /** Constructs a Gaussian blur and computes the backing surface size.
  *
  * @param aRect The coordinates of the surface to create in device units.
  *
  * @param aSigma The blur sigma.
  *
  * @param aDirtyRect A pointer to a dirty rect, measured in device units, if
  *   available.  This will be used for optimizing the blur operation. It is
  *   safe to pass nullptr here.
  *
  * @param aSkipRect A pointer to a rect, measured in device units, that
  *   represents an area where blurring is unnecessary and shouldn't be done
  * for speed reasons. It is safe to pass nullptr here.
  *
  * @param aFormat The format of the surface's data.
  *
  * @param aClamp Whether clamping at border pixels is required.
  */
 GaussianBlur(const Rect& aRect, const IntSize& aSpreadRadius,
              const Point& aSigma, const Rect* aDirtyRect,
              const Rect* aSkipRect, SurfaceFormat aFormat = SurfaceFormat::A8,
              bool aClamp = false);

 explicit GaussianBlur(const Point& aSigma, bool aClamp = false);

 GaussianBlur();

 void Init(const Rect& aRect, const IntSize& aSpreadRadius,
           const Point& aBlurSigma, const Rect* aDirtyRect,
           const Rect* aSkipRect, SurfaceFormat aFormat = SurfaceFormat::A8,
           bool aClamp = false);

 ~GaussianBlur();

 /**
  * Return the size, in pixels, of the surface we'd use.
  */
 IntSize GetSize() const;

 /**
  * Return the format of the blur data.
  */
 SurfaceFormat GetFormat() const;

 /**
  * Return the stride, in bytes, of the surface we'd use.
  */
 int32_t GetStride() const;

 /**
  * Returns the device-space rectangle the surface covers.
  */
 IntRect GetRect() const;

 /**
  * Return a pointer to a dirty rect, as passed in to the constructor, or
  * nullptr if none was passed in.
  */
 Rect* GetDirtyRect();

 /**
  * Return the spread radius, in pixels.
  */
 IntSize GetSpreadRadius() const { return mSpreadRadius; }

 /**
  * Return the blur sigma.
  */
 Point GetBlurSigma() const { return mBlurSigma; }

 /**
  * Return the blur radius, in pixels.
  */
 IntSize GetBlurRadius() const { return mBlurRadius; }

 /**
  * Return the skip rect.
  */
 IntRect GetSkipRect() const { return mSkipRect; }

 /**
  * Return the minimum buffer size that should be given to Blur() method.  If
  * zero, the class is not properly setup for blurring.  Note that this
  * includes the extra three bytes on top of the stride*width, where something
  * like gfxImageSurface::GetDataSize() would report without it, even if it
  * happens to have the extra bytes.
  */
 size_t GetSurfaceAllocationSize() const;

 /**
  * Perform the blur in-place on the surface backed by specified surface data.
  * The size must be at least that returned by GetSurfaceAllocationSize() or
  * bad things will happen.
  */
 void Blur(uint8_t* aData, int32_t aStride, const IntSize& aSize,
           SurfaceFormat aFormat = SurfaceFormat::UNKNOWN) const;

 /**
  * Calculates a blur radius that, when used with box blur, approximates a
  * Gaussian blur with the given standard deviation.  The result of this
  * function should be used as the aBlurRadius parameter to GaussianBlur's
  * constructor, above.
  */
 static IntSize CalculateBlurRadius(const Point& aStandardDeviation);
 static Float CalculateBlurSigma(int32_t aBlurRadius);

private:
 /**
  * A rect indicating the area where blurring is unnecessary, and the blur
  * algorithm should skip over it.
  *
  * This is guaranteed to be 4-pixel aligned in the x axis.
  */
 IntRect mSkipRect;

 /**
  * The device-space rectangle the backing surface covers.
  */
 IntRect mRect;

 /**
  * A copy of the dirty rect passed to the constructor. This will only be valid
  * if mHasDirtyRect is true.
  */
 Rect mDirtyRect;

 /**
  * The spread radius, in pixels.
  */
 IntSize mSpreadRadius;

 /**
  * The blur sigma (standard deviation).
  */
 Point mBlurSigma;

 /**
  * The blur radius, in pixels.
  */
 IntSize mBlurRadius;

 /**
  * The format of the data passed to Blur()
  */
 SurfaceFormat mFormat = SurfaceFormat::UNKNOWN;

 /**
  * Whether clamping at border pixels is required.
  */
 bool mClamp = false;

 /**
  * The stride of the data passed to Blur()
  */
 int32_t mStride = 0;

 /**
  * The minimum size of the buffer needed for the Blur() operation.
  */
 size_t mSurfaceAllocationSize = 0;

 /**
  * Whether mDirtyRect contains valid data.
  */
 bool mHasDirtyRect = false;

 bool Spread(uint8_t* aData, int32_t aStride, const IntSize& aSize,
             SurfaceFormat aFormat) const;

 friend class DrawTargetSkia;

 bool BlurSkSurface(SkSurface* aSurface) const;
};

}  // namespace gfx
}  // namespace mozilla

#endif /* MOZILLA_GFX_BLUR_H_ */